What methods are recommended for malaria prevention?

Malaria Prevention

Malaria prevention requires a dual approach combining appropriate chemoprophylaxis based on the destination's resistance patterns and rigorous personal protection measures against mosquito bites, particularly between dusk and dawn when Anopheles mosquitoes feed. 1

Personal Protection Measures (Essential for All Travelers)

All travelers to malarious areas must implement vector control measures regardless of chemoprophylaxis use, as no preventive method provides 100% protection. 1

Nighttime Protection (Dusk to Dawn)

• Remain in well-screened, air-conditioned areas during evening and nighttime hours when Anopheles mosquitoes are most active 1
• Use insecticide-treated mosquito nets when sleeping, ensuring nets are tucked under the mattress 1, 2
• Wear long-sleeved clothing and long trousers if outdoors after sunset 1

Insect Repellents

• Apply DEET-containing repellents to exposed skin, as these are the most effective repellents available 1
• Use DEET sparingly and avoid high-concentration products on children's skin to minimize risk of toxic encephalopathy 1
• Do not apply DEET to children's hands, near eyes or mouth, or on irritated skin 1
• Wash DEET-treated skin after coming indoors 1
• Apply permethrin to clothing for additional mosquito protection 1
• Use pyrethrum-containing flying-insect spray in living and sleeping areas during evening and nighttime 1

Chemoprophylaxis Selection

The choice of chemoprophylaxis depends critically on the destination's chloroquine resistance patterns, with chloroquine reserved only for areas without resistance and mefloquine or atovaquone-proguanil for resistant regions. 1, 3

For Chloroquine-Sensitive Areas

Chloroquine remains the drug of choice for areas without chloroquine-resistant P. falciparum, including Central America west of the Panama Canal, Haiti, Dominican Republic, the Middle East, and Egypt 1, 3

• Adult dosage: 500 mg chloroquine phosphate (300 mg base) once weekly 1, 3
• Begin 1-2 weeks before travel to ensure adequate blood levels and identify side effects early 1, 3
• Continue weekly during travel and for 4 weeks after leaving the malarious area 1, 3
• Hydroxychloroquine may be substituted if chloroquine is not tolerated 1, 3

For Chloroquine-Resistant Areas

For areas with chloroquine-resistant P. falciparum (most of sub-Saharan Africa, Southeast Asia, Amazon basin), mefloquine or atovaquone-proguanil are first-line options. 1, 4

Mefloquine

• Adult dosage: 250 mg once weekly for 4 weeks, then every other week 1
• Begin 1-2 weeks before travel 1
• Continue during travel and for 4 weeks after departure 1
• Avoid in patients with history of convulsions, epilepsy, or serious psychiatric disorder due to neuropsychiatric side effects occurring in approximately 0.01% of users 1

Atovaquone-Proguanil

• Adult dosage: One tablet (250 mg atovaquone/100 mg proguanil) daily 5
• Begin 1-2 days before travel 5
• Continue daily during stay and for 7 days after return 5
• Take with food or milky drink at the same time each day 5
• Contraindicated in severe renal impairment (creatinine clearance <30 mL/min) for prophylaxis 5

Doxycycline (Alternative)

• Begin 1-2 days before travel to malarious area 6
• Continue daily while in malarious area and for 4 weeks after leaving 6
• Should not exceed 4 months of continuous use 6
• Advise patients to avoid excessive sunlight due to phototoxicity risk 6
• Take with liberal fluids to reduce esophageal irritation 6

Chloroquine Plus Proguanil

The combination of chloroquine (300 mg base weekly) plus proguanil (200 mg daily) provides substantial but incomplete protection in areas with limited to moderate chloroquine resistance, though it is less effective than mefloquine 1, 2

Critical Timing and Compliance Issues

Compliance with chemoprophylaxis is essential, as most malaria deaths in travelers occur in those who do not fully comply with prophylactic regimens. 1, 7

• Among U.S. residents with imported malaria in 2018,95% did not adhere to or did not take CDC-recommended chemoprophylaxis 7
• Only 24.5% of U.S. residents with imported malaria reported taking any chemoprophylaxis 7
• Common reasons for nonadherence include prematurely stopping medication after leaving endemic areas, forgetting doses, and experiencing side effects 7

Risk Assessment Considerations

Sub-Saharan Africa poses the highest malaria risk for U.S. travelers, accounting for 85% of imported cases and 73% of malaria deaths despite representing only a small fraction of travel volume. 1, 4, 7

• Risk varies by accommodation type: tourists in air-conditioned hotels face lower risk than backpackers, missionaries, or Peace Corps volunteers 1
• Urban versus rural exposure matters: most travelers to Asia and South America stay in urban/resort areas with limited risk, while Africa travelers often spend evening hours in high-risk rural areas 1
• For "conventional" stays (<1 month in urban areas) in low-risk tropical Asia and Americas, the infection risk (≤1/100,000) may equal or be lower than serious adverse effects from chemoprophylaxis 2

Special Populations

Pregnant Women

• Pregnant women should avoid travel to malarious areas when possible 8
• Among 19 pregnant women with malaria in 2018, only one reported taking chemoprophylaxis 7
• Chloroquine is considered safe in pregnancy for chloroquine-sensitive areas 8

Children and Infants

• Breast-fed infants require separate chemoprophylaxis and are not protected through maternal chemoprophylaxis 9
• Mefloquine can be given to infants and young children for chloroquine-resistant areas 9
• Use lower DEET concentrations on children and avoid application to hands 1

Renal Impairment

• Atovaquone-proguanil should not be used for prophylaxis in severe renal impairment (creatinine clearance <30 mL/min) 5
• No dosage adjustments needed for mild to moderate renal impairment 5

Post-Travel Surveillance

Malaria symptoms can develop as early as 8 days after initial exposure or as late as several months after departure, even after chemoprophylaxis has been terminated. 1, 3

• Any febrile illness after returning from endemic areas requires immediate medical evaluation with thick and thin malaria smears 1
• Delay in appropriate therapy can have serious or fatal consequences 1
• Most patients (92.6%) develop symptoms within 90 days of returning 7

Common Pitfalls to Avoid

• Never assume chemoprophylaxis alone provides complete protection—personal protection measures are equally critical 1
• Do not discontinue chemoprophylaxis immediately upon leaving endemic areas—continue for 4 weeks (or 7 days for atovaquone-proguanil) 1, 5
• Avoid taking antacids, kaolin, or cimetidine with chloroquine, as these reduce absorption or increase plasma levels 8
• Do not use chloroquine for areas with documented resistance, as P. falciparum resistance is now widespread except in specific regions 1, 4
• Travelers visiting friends and relatives (77% of U.S. civilian malaria cases) are at particularly high risk and require aggressive counseling 7, 2